Question

(1) Field Control Unit

The field control unit is generally far away from the control center and installed near the site. Its highly modular structure can be configured as a process control unit with a range of sizes from several monitoring points to hundreds of monitoring points depending on the needs of process monitoring and control.

The structure of the field control unit is based on a certain logical or physical sequence installed in the board box by a number of functionally distributed boards (or card components). Each field control unit and its connection with the control management level are connected by bus. Implement information exchange.

The hardware configuration of the field control unit needs to complete the following:

Configuration of plug-ins Configure host plug-ins (CPU plug-ins), power plug-ins, I/O plug-ins, communication plug-ins, and other hardware devices according to the requirements of the system and the scale of control;

Hardware Redundancy Configuration Redundant configuration of key devices is an important means to improve the reliability of DCS. DCS can usually implement redundant configurations for host plug-ins, power plug-ins, communication plug-ins, and network and key I/O plug-ins.

Hardware Installation Different DCSs, for the installation of various plug-ins in the plug-in box, have corresponding provisions in the logical or physical sequence. In addition, the field control unit is usually divided into basic type and extended type. The so-called basic type is a variety of plug-ins installed in a plug-in box, but more often require an extensible structure, that is, a field control unit also includes A number of digital input/output expansion units are connected to each other using a bus.

In essence, the structural form and configuration requirements of the field control unit are consistent with the hardware configuration of the modular PLC.